This invention relates to wire coiling machines.
The demands required of coiling machines during the period from the 1940's to the present have increased markedly. For example, the coiling of resistance wire for sophisticated instrumentation has become extremely precise and exacting. At times, the wire involved is only 0.003 inches in diameter, i.e. about 0.0005 inches more than human hair. With wire this fine, the drive torque on the coiling rolls has a drastic effect on the operation. Yet, no machines in existence, including those of my previous patents, are of a design such that there is no drive torque to influence coiling pressure on the delicate wire.
Coiling machines of the 1940's, see e.g. my U.S. Pat. No. 2,227,602 employed broadfaced rubber rolls which picked up power directly from the spinning arbor and had to be angled to coil at all. So, the machine was built, of necessity, with compound angling sectors to the outside of each of the two rolls. It was not possible with such a construction to "hang" the coiling rolls. Thus, even their weight imparted pressure to the wire. And, transfer of coiling power from the rear of the machine caused torque imbalance between the two coiling rolls at the front of the machine. Actually when coiling the larger diameter wire then involved, this was not a significant problem. Subsequent coiling machines brought power from the rear of the machine by speed reduction and flexible cables so that the coiling rolls could be angled and have heavy coiling power. See e.g. my U.S. Pat. No. 3,082,810. Since surface speed synchronization of spinning arbor and back-up rings was only approximate on such machines, the two cooperative back-up rings were designed never to touch the spinning arbor. Hence, drive torque added to coiling pressure of one of the coiling rolls, i.e. the rear roll, and substracted from the other cooperative coiling roll, i.e. the front roll.
As a result of my more recent efforts, there is disclosed in copending application Ser. No. 7,158 now U.S. Pat. No. 4,208,896, special steel back-up rings which pick up their coiling power by steel-to-steel contact with the spinning arbor itself to coil delicate wire. It will be realized that very small forces are involved with spinning operations on such delicate wire. At times, the spinning arbors themselves are only 0.015 inches in diameter, so that the pick-up power of the two steel back-up rings biased against such small spinning arbors is minute, as are all the forces involved.
To coil such fine wire sizes as presently necessary, and do so accurately and efficiently, it has been found important to obtain completely equal coiling pressure from both coiling rolls. It is also important that there be resilience of cushioning between the forming roll portion of the coiling roll, and the wire being coiled around the arbor. And if fast production is to be maintained, there must be excellent heat dissipation while coiling.
Development of a machine to satisfy these exacting requirements has resulted in a novel assembly which not only meets these requirements but surprisingly enough, is actually simpler in construction than prior machines.